What types of move should the speed factor affect?

dc42

The purpose of M221 is to change the extrusion amount, not the speed.

Danal

@dc42 said in What types of move should the speed factor affect?:

The purpose of M221 is to change the extrusion amount, not the speed.

Stand alone extrusion, I agree, that probably shouldn't be called anything to do with 'speed'.

When extrusion occurs in coordination with other moves, how can one change the amount without changing the speed?

M220 is for dynamic adjustments during printing, and E moves on the same line, like G1 Xnnn Ynnn Ennn, are the most common thing during printing. And those moves must change the speed of something, if more filament is to come out during that move.

DocTrucker

My vote would be speed up travel moves, leave retraction/unretraction, and z-hops. Ensure that maximum speeds from config can't be overrided.

littlehobbyshop

Perhaps a parameter on M220. Default (with no parameters) as it stands with the option to change its behaviour with an optional parameter.
Of course that would mean the behaviour would have to be set in config.g if you wanted anything other than default and it would have to maintain that behaviour when M220 is sent without parameters to allow changes from DWC.

FBG

@dc42 I agree. +1

TC

Are moves during the tool change prcedure also travel moves? In that case it would be very useful not to include them, because a tool change using for example a T-lock is a speed sensible process.

tobias_munich

I agree to @dc42 's proposal

dc42

@TC said in What types of move should the speed factor affect?:

Are moves during the tool change prcedure also travel moves? In that case it would be very useful not to include them, because a tool change using for example a T-lock is a speed sensible process.

Yes, they are. But I can exempt them separately.

dc42

So the following seem to be agreed:

Printing moves (i.e. moves containing both XY movement and extrusion) should be affected by M220
Extruder-only movements (retract/reprime) should not be affected by M220
Movements within tool change files should not be affected
Homing moves already are not affected

Not yet decided:

Should all moves generated by any macro files (not just tool change files) be unaffected?
Should non-extruding G1 moves be affected (i.e. travel moves when 3D printing)? For CNC machines and laser cutters, the answer is obviously yes.

I am leaning towards the following:

Moves generated by commands in a macro file should not be affected
Other travel moves should be affected

TC

@dc42 I agree, that sounds like a good way to do it.

danzaywer

@dc42 I agree

DocTrucker

I'd be tempted to exclude z only moves so z hop can be dialled-in, in a similar way to retraction and the speed up not effect it. Negligable effect on overall build time in most builds.

Phaedrux

@DocTrucker said in What types of move should the speed factor affect?:

I'd be tempted to exclude z only moves so z hop can be dialled-in, in a similar way to retraction and the speed up not effect it. Negligable effect on overall build time in most builds.

Perhaps M207 could be extended to include Z hop speed?

https://duet3d.dozuki.com/Wiki/Gcode#Section_M207_Set_retract_length

deckingman

Does the speed factor override also override the acceleration rate or just the speeds after the acceleration phase? Because if it doesn't affect the acceleration rate, then short moves like Z hop are likely to be unaffected because they will either be accelerating or decelerating and never attain the set Z speed in any case.

dc42

@Phaedrux said in What types of move should the speed factor affect?:

@DocTrucker said in What types of move should the speed factor affect?:

I'd be tempted to exclude z only moves so z hop can be dialled-in, in a similar way to retraction and the speed up not effect it. Negligable effect on overall build time in most builds.

Perhaps M207 could be extended to include Z hop speed?

https://duet3d.dozuki.com/Wiki/Gcode#Section_M207_Set_retract_length

Z-hop is generally so short that in practice it is acceleration-limited.

dc42

@deckingman said in What types of move should the speed factor affect?:

Does the speed factor override also override the acceleration rate or just the speeds after the acceleration phase? Because if it doesn't affect the acceleration rate, then short moves like Z hop are likely to be unaffected because they will either be accelerating or decelerating and never attain the set Z speed in any case.

Acceleration and jerk are not affected by M220.

peter247

@dc42

I'm with the only X and Y moves .

Any news if this is going to be changed ?

dc42

From the version 3.1.0 change list at https://github.com/Duet3D/RepRapFirmware/blob/v3-dev/WHATS_NEW_RRF3.md:

The speed factor (M220) is no longer applied to extruder-only moves or to movement commands in system or user macro files

Antomy5

Thanks for asking this thread. I don't know much about this speed factor. But I am interested and I would like to get some more details.